Efficacy of Prayer

Skeptical Inquirer, March, 2000 by Irwin Tessman, Jack Tessman

A Critical Examination of Claims

The "landmark study" of Byrd and the recent confirmation attempt by Harris et al., both claiming therapeutic benefits of intercessory prayer, are shown to be invalid. One was improperly designed, the other fallaciously analyzed--and the two contradict each other.

The therapeutic power of prayer is a recurring theme among many proponents of alternative medicine. One can imagine a natural explanation for the alleged benefits: a psychological boost from the belief that a supernatural power is on your side. But what if you are unaware that people are praying for you? Such intercessory prayers could only work through a supernatural agency.

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Investigating the efficacy of intercessory prayer was given scientific legitimacy by Francis Galton, the father of biometry and a central figure in the founding of modern statistical analysis. In classic memoirs, Galton (1872, 1883) argued that regardless of how the prayers "may be supposed to operate," the "efficacy of prayer... is a perfectly appropriate and legitimate subject of scientific inquiry" because it can be rested statistically, as he then demonstrated. [1]

A Landmark Study

A celebrated study performed at San Francisco General Hospital by Randolph C. Byrd reported that patients in a cardiac care unit received statistically significant benefits from intercessory prayers (Byrd 1988). That study has attained special status within the alternative medicine community and has been reprinted as a "landmark study" (Byrd 1997).

In the same skeptical spirit that motivates one to seek the flaw in the design of a perpetual motion machine, we have examined Byrd's study, as others have done (Posner 1990; Sloan et al. 1999; Witmer and Zimmerman 1991), to seek a natural explanation to rival the supernatural one.

We believe a serious flaw exists in his critical Table 3, a flaw that raises doubts about the table's validity. That table reports the overall outcome for patients admitted to the cardiac care unit. Upon admission, they were entered randomly into one of two groups: an intercessory prayer group or a control group (192 and 201 patients). The outcome was recorded as good, intermediate, or bad. [2] Byrd found that compared to the control group, the prayer group had an excess of good outcomes and a deficit of bad outcomes, a significant difference in favor of the prayer group with P [less than] 0.01 (Byrd's Table 3). The study was necessarily intended to be double blind. Byrd writes: "The patients, the staff and doctors in the unit, and I remained 'blinded' throughout the study."

Unfortunately, that was nor the case at a critical point. Byrd's Table 3, which might best have been constructed by a panel of "blinded" doctors, was constructed by Byrd alone. But it was done in response to criticism of an earlier version of his manuscript, the writing of which had already required that the code be broken. Thus Byrd was no longer blinded when he determined the answer to the key question of which did better, the intercessory prayer group or the control group (Byrd, personal communication).

Because the table was apparently constructed from computer-stored data using objectively stated criteria that did not involve Byrd in any personal evaluation of individual cases, the lack of blinding might have had no effect. Although blind evaluation is dearly preferable, the use of unblinded analysis could be defended were it completely computer generated. However, the criteria he chose for evaluating the patients' outcomes were formulated after the data were collected and when Byrd was unblinded. That is an unreliable approach. The criteria should have been selected before the start of the study.

The claim of blindedness is erroneous in yet another respect (one aspect of which has already been mentioned [Witmer and Zimmerman 1991]). In his acknowledgments, Byrd thanks "Mrs. Janet Greene for her dedication to this study," but without any elaboration of her role. In a later publication (Byrd with Sherrill 1995) we leam that Janet Greene was hired "... to be our coordinator.... Janet entered names of all the volunteer patients into a computer that randomly divided them into two groups. ... half of the patients--only Janet knew who they were--were prayed for daily by our intercessors.... She kept derailed records of all patients in both groups." Thus the very coordinator of the study was completely unblinded. Once patients were assigned to one of the two groups, Greene should have had no further contact with the hospital.[3]

Byrd's evidence for supernatural intervention, if true, would arguably be one of the most remarkable scientific demonstrations of the last millennium. To be credible, however, it requires, among other things (Posner 1990; Sloan et al. 1999; Witmer and Zimmerman 1991), considerably more attention to strict blindedness. In the absence of that credibility, its status, not to mention the "landmark" label, is highly dubious.

A Confirmation Attempt

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Efficacy of Prayer

Skeptical Inquirer, March, 2000 by Irwin Tessman, Jack Tessman

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